NATIONAL

YIELDS ON FOUR-YEAR Treasury notes fell sharply to 7.29 percent in Tuesday's auction, the lowest in more than eight years. The Treasury Department sold $7 billion in notes with the average yield down from 8.43 percent at the last auction on Dec. 31. The rate was the lowest since 6.84 percent on Sept. 7, 1977.

DOMESTIC AUTO SALES slid in mid-March to 17.2 percent below a year earlier, as analysts said Tuesday that falling interest rates had tarnished the glitter of cut-rate financing. The seven U.S. automakers sold 226,712 cars from March 11-20, compared with sales of 273,822 in the year-ago period. For the year through March 20, sales totaled 1,661,152, down 4.6 percent from 1,740,801 in the year-ago period, the automakers said. The mid-March decline came after the larger automakers, who had been offering 7.7 percent financing on many models, raised their loan rates to 9.9 percent.

CBS INC. reiterated Tuesday that it intends to remain independent, following reports that it may have received a takeover offer from Marvin Davis, a Denver millionaire and former owner of Twentieth Century-Fox Film Corp. CBS said it was not in any negotiations about ownership or control of the company. Davis could not be reached for comment.

INTERNATIONAL BUSINESS MACHINES CORP. Chairman John Opel Tuesday said he will relinquish his position on June 1. The computer maker said Opel, 61, will remain on its board of directors and will become chairman of the executive committee, replacing Frank Cary on April 28. Cary will continue to be a director, the company said. John Akers, IBM's president and chief executive officer, will succeed Opel as chairman and retain his current positions, a spokeswoman said. An analyst who follows IBM said he was not surprised by the move. "Opel wasn't running the company - Akers was the chief executive officer," he said. The analyst said he did not think the changes were related to IBM's flat results for 1985.

GENERAL MOTORS CORP. plans to spend a record $10 billion in 1986 on new plants and equipment, the giant automaker said in its annual report. The company's capital budget for this year includes several major projects, including a new auto assembly plant in Fairfax, Kan., a new Truck & Bus Group plant in Fort Wayne, Ind., and the first construction work on the Saturn Corp. plant in Spring Hill, Tenn.

TED TURNER, after months of financial uncertainty, officially closed his $1.5 billion acquisition of MGM-UA Entertainment Co. The studio, now a subsidiary of Turner Broadcasting System Inc., immediately announced the promotion of Alan Ladd Jr. to chairman and chief executive officer, replacing Frank Rothman, who had agreed to leave the studio once the acquisition was complete. The closing of the deal also marked the $470 million sale of United Artists to financier Kirk Kerkorian, who had held 50.1 percent of the stock in MGM-UA. The path was cleared for Turner's acquisition with the sale last week of $1.4 billion in so-called "junk bonds" - low-rated, high-interest securities. To ease the financial burden, Turner has said he intends to sell most of the studio's assets, while keeping most of its vast library of classic films to enhance the programming of his cable television station WTBS.

ELSEWHERE IN THE NATION: The Federal Deposit Insurance Corp. has voted to retain current restrictions on money market deposit account transfers. The FDIC had previously considered easing the limits so that businesses could take better advantage of the interest-bearing accounts. ... The chairmen of Pennzoil Co. and Texaco Inc. met in a private session in New York Tuesday to try to negotiate a settlment in the $11.1 billion legal battle between the two oil companies. Discussions reportedly will continue. ... Toyota Motor Corp. said it will begin car production at its Illinois plant in early 1988, about six months sooner than originally planned.

FLORIDA

EASTERN AIRLINES of Miami has deferred payment of the quarterly dividends due on May 15 on the company's $2.69 cumulative preferred, $3.20 cumulative preferred and the $3 cumulative convertible junior preferred stock. On May 15, Eastern's arrearages will be 5.75 quarters on the two senior issues and 11 quarters on the junior preferred issue.

NORTHEASTERN INTERNATIONAL AIRWAYS President and founder Stephen L. Quinto said he is looking for buyers for the Fort Lauderdale airline's remaining assets, worth about $7 million. The airline's lone leased MD-80 aircraft was repossessed three weeks ago in bankruptcy court proceedings. Northeastern shut down last fall after filing for bankruptcy court protection from its creditors about a year ago.

CITYFED FINANCIAL CORP. of Palm Beach and PNC Financial Corp. of Pittsburgh on Tuesday reached a definitive agreement for the sale of PNC's mortgage banking subsidiary, the Kissell Co., to City Federal for a cash purchase price of $103.2 million. The transaction will add about $7 billion to the mortgage servicing portfolio of CityFed and will place it among the four largest mortgage servicers in the country, when measured by total portfolio size, PNC Financial said. Kissell will retain its name.

ELSEWHERE IN FLORIDA: American Capital Corp. of Miami has filed a registration statement with the U.S. Securities and Exchange Commission to offer 1.5 million shares of common stock. The statement is not yet effective, but Drexel Burnham Lambert is to be the underwriter. ... Southeast Banking Corp. declared a quarterly dividend of 30 cents per share on common stock, payable April 11 to shareholders of record March 31. A dividend of $1.015 per share on the $4.06 cumulative dividend preferred stock also will be paid, with the same dates of record. Dividends also were declared on Series A non-voting adjustable rate preferred stock and Series B and C non-voting convertible preferred stock. The dividends on Series A and B, payable March 31 to shareholders of record today, are $1.088 and $1.25 respectively. The Series C dividend is $1.25 per share payable April 11 to shareholders of record March 31. ... Bonina Insurance of Boca Raton has merged with Republic Hogg Robinson Inc., a national retail insurance broker that has an office in Miami. Bonina will remain in Boca Raton. ... Standard & Poor's Corp. has placed Resorts International's B+ subordinated debt on its creditwatch surveillance list with negative implications. Resorts International is based in North Miami. ... Franklin T. Julian has been named executive vice president of marketing and sales for Mitel Corp. of Kanata, Ontario. Mitel's U.S. headquarters is in Boca Raton.